1. Field of the Invention
The present invention relates to a bonding apparatus and more particularly to a transducer used in a bonding apparatus.
2. Prior Art
A method that uses ultrasonic pressure welding is known as one of the methods for mounting electronic parts such as the one formed with bumps, etc. to lead frames, substrates, etc. In this ultrasonic pressure welding method, an ultrasonic vibration is applied while the bumps of the electronic parts are pressed against the substrate, thus bonding the joining surfaces by mutual friction between the surfaces.
So as to allow an continuous execution of the above-described bonding operation and a pre-bonding operation that mounts the electronic part (which is the object to be processed) in a specified position on the surface to which the electronic part is to be bonded, a transducer to which the ultrasonic vibration is fastened is provided with a passage that communicates between a piping attachment and a suction holding port which is used for suction holding the electronic part.
The suction holding port is, in order to cause the ultrasonic vibration to act efficiently on the electronic part, disposed at a position that corresponds to the crest of the ultrasonic vibration in the transducer. In other words, the suction holding port is provided in an area where the amplitude of the standing wave shows the maximum value. On the other hand, in order to avoid effects on the ultrasonic vibration, the air pressure piping that applies suction to the electronic part via the passage is disposed at a position that corresponds to the node of the ultrasonic vibration.
In such a construction as described above, however, the distance from the suction holding port to the air pressure piping is long. As a result, there is a specified time delay before the on-off switching of the negative pressure via the air pressure piping acts on the suction holding port. The operating response characteristics are thus poor. For solving this problem, in Japanese Patent Application Laid-Open (Kokai) No. H11-307588, the air pressure piping and transducer are designed so as to be connected and separated. However, this structure has drawbacks. The number of moving components is high, and the construction is thus complicated.
Accordingly, the object of the present invention is to provide a transducer that can suppresses the deleterious effects in terms of vibration characteristics that are exerted by the air pressure piping on the transducer.
The above object is accomplished by a unique structure for a transducer which is used in a bonding apparatus and has a passage communicating between a piping attachment and a suction holding port that suction-holds an object to be processed (or, for instance, to be bonded), the object to be processed being suction-held by suction applied via the passage; and in the present invention, an air pressure piping used for the suction is connected to the piping attachment by a connecting member that can suppresses effects (influence) of reaction force of the air pressure piping.
The above object is accomplished by another unique structure for a transducer which is used in a bonding apparatus and has a passage communicating between a piping attachment and a suction holding port that suction-holds an object to be processed (or, for instance, to be bonded), the object to be processed being suction-held by suction applied via the passage; and in the present invention, an air pressure piping used for the suction is connected to the piping attachment by a connecting member that is made of a foam resin material.
In the above structure of the present invention, the air pressure piping that is used for suction holding is connected to the piping attachment via a connecting member formed from a foam resin material. Accordingly, the effects of the reaction force from the air pressure piping on the ultrasonic vibration of the transducer can be effectively suppressed. The reason for this is, though unclear, that while the reaction force F is defined as F=ma+cv+kx (m is the mass, a is the acceleration, c is the viscosity coefficient, v is the velocity, k is the spring constant, and x is the displacement), the mass m and viscosity coefficient c of the connecting member made of a foam resin material are much smaller than those of a metal or non-foam resin material, so that the connecting member can suppress the effects of the reaction force on ultrasonic vibrations that have a large acceleration a and velocity V.
In the above structure, the foam resin material is an independent foam body.
Since the foam resin material is formed as an independent foam body, the air-tightness with respect to suction is ensured.
Furthermore, the foam resin material is a styrol resin.
Since the foam resin material is a styrol resin, the connecting member can be constructed especially inexpensively and with a light weight. Furthermore, since the amount of shrinkage with respect to the suction of air pressure devices such as a vacuum pump, etc. is small compared to that of a soft material such as a urethane resin, etc., there is no loss of the response characteristics of the suction holding operation.
In addition, the connecting member can be provided with an air-tight layer that is formed on an inner circumferential surface thereof so as to face the passage.
With the air-tight layer formed on the inner circumferential surface of the connecting member, the air-tightness of the connecting member is heightened even further.
Furthermore, in the present invention, the passage is provided within a specified range from a point of maximum amplitude of the transducer in the direction of length of the transducer.
By way of positioning the passage within a specified range that extends from the point of maximum amplitude of the transducer in the direction of length of the transducer, the distance from the suction holding port disposed at the point of maximum amplitude to the piping attachment can be shortened, and as a result the response characteristics of the suction operation is improved.
Furthermore, the passage is disposed in the direction perpendicular to the direction of length of the transducer.
Since the passage is disposed in the perpendicular direction to the direction of length of the transducer, the length of the passage can be minimized, and the response characteristics of the suction operation is improved.
In addition, the transducer can be provided with a vibrator at one end thereof and a weight that has a mass substantially equal to that of the vibrator at another end thereof.
With a vibrator at one end of the transducer and a weight having a mass that is substantially equal to that of the vibrator at other end, any mass imbalance in the transducer is suppressed, and the vibration transmission efficiency is improved.